package stdlib;
/**
 * A generic subscriber which a class can implement when it wants to be informed
 * of changes in published objects.
 *
 * @param <T> the type of the publisher object
 * @param <U> the type of the optional data argument
 * @see Subscriptions
 */
public interface Subscriber<T, U> {
	/**
	 * This method is called whenever the published object is changed.
	 *
	 * @param publisher the object which was the source of the notification.
	 * @param data an optional data parameter which encapsulates any
	 *   additional data about the event
	 */
	void update(T publisher, U data);
}